Portable electronic devices such as smart phones, tablets, notebooks and other electronic devices have become an everyday need in the way we communicate and interact with others. The frequent use of these devices may require a significant amount of power, which may easily deplete the batteries attached to these devices. Therefore, a user is frequently needed to plug in the device to a power source, and recharge such device. This may require having to charge electronic equipment at least once a day, or in high-demand electronic devices more than once a day.
Such an activity may be tedious and may represent a burden to users. For example, a user may be required to carry chargers in case his electronic equipment is lacking power. In addition, users have to find available power sources to connect to an electronic device. Lastly, users must plugin to a wall or other power supply to be able to charge his or her electronic device. However, such an activity may render electronic devices inoperable during charging.
Current solutions to this problem may include devices having rechargeable batteries. However, the aforementioned approach requires a user to carry around extra batteries, and also make sure that the extra set of batteries is charged. Solar-powered battery chargers are also known, however, solar cells are expensive, and a large array of solar cells may be required to charge a battery of any significant capacity. Other approaches involve a mat or pad that allows charging of a device without physically connecting a plug of the device to an electrical outlet, by using electromagnetic signals. In this case, the device still requires to be placed in a certain location for a period of time in order to be charged. Assuming a single source power transmission of electro-magnetic (EM) signal, an EM signal gets reduced by a factor proportional to 1/r2 in magnitude over a distance r, in other words, it is attenuated proportional to the square of the distance. Thus, the received power at a large distance from the EM transmitter is a small fraction of the power transmitted. To increase the power of the received signal, the transmission power would have to be boosted. Assuming that the transmitted signal has an efficient reception at three centimeters from the EM transmitter, receiving the same signal power over a useful distance of three meters would entail boosting the transmitted power by 10,000 times. Such power transmission is wasteful, as most of the energy would be transmitted and not received by the intended devices, it could be hazardous to living tissue, it would most likely interfere with most electronic devices in the immediate vicinity, and it may be dissipated as heat.
In yet another approach such as directional power transmission, it would generally require knowing the location of the device to be able to point the signal in the right direction to enhance the power transmission efficiency. However, even when the device is located, efficient transmission is not guaranteed due to reflections and interference of objects in the path or vicinity of the receiving device.
For the foregoing reasons, there is a need for a wireless power transmission system where electronic devices may be powered without requiring extra chargers or plugs, and where the mobility and portability of electronic devices may not be compromised. Therefore, a wireless power transmission method solving the aforementioned problems is desired.
Wearable portable electronic devices, such as headsets, smart-watches, light key-chains and other such wearable equipment may include batteries, for performing their intended functions. When batteries run out, such electronic devices may be inoperable and are often rendered unusable. This may be a burden for users which may need to carry extra batteries, whenever they go out, in case the aforementioned electronic devices run out of power. In the worst case scenario, batteries in such devices may not be replaceable. Thus, these devices may no longer be useful and may therefore be disposed as waste. This may have cost implications as well as environmental implications because users may not only have to re-purchase items, but also produce waste which may pollute the environment. For the foregoing reasons, there may be a need for increasing the battery life of the aforementioned electronic devices.
Wearable portable electronic devices such as headsets, smart-watches, light key-chains, and other similar devices, have also become an everyday need in the way we communicate, socialize and interact with others, and go about ordinary tasks, such as dieting or exercising. The frequent use of these devices may require a significant amount of power, which may easily deplete the batteries attached to these devices. Therefore, a user is frequently needed to plug in the device to a power source, and recharge such device. This may be inconvenient and troublesome if the user forgets to plug in or otherwise charge a device, the device may run out of power and be of no use to the user until the user is again able to charge the device.
Wireless power transmission may be an answer for the situation described above, however wireless power transmission may usually need a transmitter and a receiver to work. There may be situations when transmitter, being the source of power, may be out of range with the receiver and hence no wireless power transmission may occur. In some situations carrying out an extra set of batteries may be a solution, however some portable electronic devices may have internal batteries that may not be easily replaced. For the foregoing reasons, there may be a need for increasing the battery life of the aforementioned electronic devices.
Wireless power transmission may be based on the extraction and conversion of power or energy from transmitted power transmission waves. One challenge that may be present during wireless power transmission is that power or energy extracted from power transmission waves may be variable due to inherent characteristics of the medium, such as air. Moreover, the power that can be extracted from power transmission waves may be zero at some instances of the wireless power transmission. The variability of the power extracted from power transmission waves may be fueled by interference produced by electronic devices, walls, metallic objects, and electromagnetic signals, among others.
What is needed is a wireless receiver, which may be integrated into a wearable portable device, and that may be capable of operating with a variable power source derived from power transmission waves. It may be also desirable to have a wireless receiver that may operate at low voltage or power levels. This may be particularly true in cases of wearable portable devices in which the power demands on the device must be kept to a minimum due to the smaller size of the wearable device.